According to DirectTV, error code 771 indicates your receiver is having difficulty communicating with the satellite dish. The most common reasons this occurs are because of bad weather, satellite obstruction or loose cables on the receiver.
DirectTV suggests customers check all cables to ensure proper connection between the wall outlets and the receiver. Clearing the satellite's view of obstructions is also a solution, provided it is safe to do so without potential for injury. If unable to clear obstruction, DirectTV suggests customers call the service department. If the satellite issues are weather related, troubleshooting should be reserved for after the weather clears. If error code 771 persists, contact the satellite company for assistance in scheduling a service appointment.